Polyurethaneurea roll covers have traditionally been manufactured by mixing and pouring reactive chemical components into a mold containing a metal core. This procedure presents problems when large rolls and/or very reactive polymer systems are employed. To address this difficulty, reactive systems have been developed which gel rapidly when cast onto a rotating roll core. Layers of material are built up to produce coatings of the desired thickness which can be used as rolls or wheels. However, these "rotational cast" systems exhibit two major deficiencies: (1) adhesion of the rotational cast polyurethaneurea to the metal core is often poor, and (2) the dynamic performance of the elastomeric roll cover is poor in that, under conditions of high load and speed, the materials undergo hysteretic heating and melt or "blow-out". This shortcoming is particularly acute for very hard roll covers used in such areas as paper manufacturing.
Commercial systems based upon polyurethane resins containing diphenyl-methanediisocyanate (MDI) have been developed for rotational casting. These resins are typically cured with a curative blend containing one or more aromatic polyamines and a long chain polyol.
U.S. Pat. No. 5,039,775 discloses a process for producing polyurea resin in which an aromatic polyamine, a specific aminobenzoate derivative and polyisocyanate are reacted.
U.S. Pat. No. 5,183,877 discloses a two-part adhesive composition utilizing a polyurea or polyurethane/urea prepolymer for improved adhesion to plastics and metals and particularly to elastomers. The two-component adhesive formulation of the invention comprises a mixture of polyamines, specifically an aminobenzoate terminated polytetramethylene glycol (AB-PTMEG) and an aromatic diamine, with an isocyanate terminated polyurea prepolymer formed by reacting the AB-PTMEG with a diisocyanate.
U.S. Pat. No. 5,548,056 discloses a laminated, untreated fiberglass reinforced polyester substrate and a cured polyureaurethane adhesive composition. The prepolymer component of the adhesive is a reaction product of a slowly reacting polyisocyanate and a polyol. The curative component comprises a diamine and, optionally, a polyol. Example 12 shows the use of a polymeric aromatic diamine of about 870 molecular weight (Polamine 650 curative) in combination with dialkylated diaminobenzene (Unilink 4100 diamine), dimethylthiotoluenediamine (Ethacure 300 diamine), and 2-methyl-1,5-pentanediamine (Dytek-A diamine).
WO 94/13722 discloses polyurethane prepolymers prepared with mononuclear aromatic diisocyanate such as toluenediisocyanate (TDI) and an aliphatic diisocyanate such as H12MDI. These prepolymers can be cured with 4,4'-methylene-bis-(3-chloro-2,6-diethylaniline) (MCDEA) to form a cured urethane elastomer. Also disclosed are prepolymers made from TDI and cured with a blend of two aromatic diamine curatives, particularly MCDEA and 4,4'-methylene-bis-(2-chloroaniline) (MBOCA). "Luvocure Polyurethan-Vernetzer" brochure from Lehmann & Voss & Co. teaches the reaction of Luvocure MUT/HT curative with TDI-polyether prepolymers. Luvocure MUT/HT curative has been analyzed as comprising a blend of MCDEA and Polamine 1000 curative, a diaminobenzoate polyether.